Machine for deep drilling



Jan. 29, 1963 G. H. DABRINGHAUS l 3,075,415

MACHINE FOR DEEP DRILLING Filed May 4, 1959 2 Sheets-Sheet 1 WM# am.

A TTOR NE YS Jan. 29, 1963 G. H. DABRINGHAus 3,075,415

MACHINE FOR DEEP DRILLING 2 Sheets-Sheet 2 Filed May 4, 1959 INVENTOR. Gus-mv H. DAsRfNoHAus ATTORNEYS 3,675,415 MACHINE FR DEEP DRKLLWG Gustav H. Dahringhans, 66970 E. Eighteen Mile Road, Utica, Mich. Filed May d, 1959, Ser. No. 8l0,685 9 Claims. (Cl. 'T7-34.7)

This invention relates to an electro-mechanical machine for deep drilling and more specically to a deep drilling machine of the type commonly referred to as a gun drilling machine.

Generally speaking, there are two types of deep drilling machines; those of the gun drilling type and those of the step drilling type. in step drilling machines, the drill is advanced a predetermined depth and then retracted to clear the chips from the hole being drilled. With machines of this type, it is impossible to obtain close tolerances on the diameter of the hole and also a very smooth finish because of the necessity of repeatedly retracting the drill from the hole being drilled.

in operation, gun drilling machines are altogether different from step drilling machines. ln a gun drilling machine, the drill is advanced continuously and the chips are removed by directing a liquid lubricant under pressure down to the tip of the drill and causing this lubricant to flow out of the hole around the shank of the drill and carry the chips with it. Thus, with gun drilling machines, the particular type or form of chip produced by the drill is very important. lf an improper chip is formed, it is irn- -possible to flush the chip out of the hole being drilled by means of lubricant.

l have found that in general, gun drilling of metals requires a relatively high speed of the drill with a relatively low feed. ln this connection, l have also determined that the relation between speed and feed is very critical; and in order to obtain satisfactory results, this relationship varies considerably depending upon the type of metal and the size of the hole being drilled. For example, in drilling a hole having a diameter of about 3/16 and a depth of about 20 in steel hea-t treated to a hardness of 40 Rockwell C, l have found that best results are obtained where the drill spindle of the machine is rotated at a speed of about 5000 rpm. and the drill is advanced about .0002 per revolution. Gn the other hand, if a 1/2" hole were drilled in fthe same steel, then best results would be obtained with a speed of the spindle at about 180() rpm. and with a feed of about .0005. ln drilling a 1/2 hole, say 20 deep, in a material such as lnconel-X, best results are obtained with a spindle speed of i200 rpm. and a feed of about .0003. if the same size hole is to be drilled in aluminum, then the speed of the spindle should be increased to about 5000 r.p.m. and the feed increased to about .0007. However, if a Mt hole about 20" deep is to be drilled in aluminum, then very good results are obtained when the spindle speed is about 10,000 to 12,000' rpm. and the feed is about .0005. in the latter case, to obtain a liner nish and a straighter hole, the speed should be reduced to about 6,000 rpm. and the feed to about .0003 per revolution.

lt is apparent, therefore, that a deep drilling machine of the gun drilling type must be capable of producing an extremely slow feed in relation to the speed of the spindle and at the same time, must be capable of producing minute changes in feed in order to obtain best results on all types of material. Experience has shown that a slight change in feed per revolution of the spindle very often produces a substantial change in the amount of drift, the finish obtained, the variation in diameter and the form of chip formed. Deep drilling machines of the continuous feed type must therefore be capable of rotating the spindle at a very high speed and at the same time produce a very slow feed in order to produce best results. The machine 075,4 l5 Patented dan. 29, i963 must furthermore be capable of changing the spindle feed in very minute increments. The machine of this invention possesses these features.

In the drawings:

FIG. l is a side elevational View of a deep drilling machine according to the present invention.

FIG. 2 is a sectional view taken along the line 2-2 in FIG. l.

FlG. 3 is a fragmentary sectional View through one of the heads of the machine taken along the line .lt-3y in FIG. 2.

PEG. 4 is a fragmentary side elevational View of a portion of the machine illustrated in FIG. l.

FIG. 5 is a sectional view taken along vthe line 5-5 in FlG. 3.

PlG. 6 is a sectional view taken along the line 6-6 in FlG. 3.

The machine illustrated in FIG. l generally comprises a base lil provided with parallel ways l2 on which two drilling units of the present invention generally designated le are mounted in opposed relation. The drilling units i4 are adjustable longitudinally of the ways l2 to accommodate therebetween a work piece lo to be drilled. Each drilling unit 14 includes a base member ld engaged with the ways l2. A drilling head Ztl is mounted on each base i8 for movement longitudinally thereof by means of a pair of spaced parallel guide rods ZZ. Head 20 is mounted on the guide rods 22 by means of low friction bearings in bosses 24 on the head 2li. Within head 20, there is journalled a spindle 26. A collet ZS is mounted on one end of spindle 2d and a liquid coupling 30 is mounted on the other end of spindle 26. Spindle 25 is provided with an axial bore 32 for conducting liquid lubricant such as oil under relatively high pressure from the coupling 30 to the hollow drill 3d retained in collet 2S. Drill 34 is of the conventional deep drilling type having an axial bore as illustrated and a carbide tip 56. The working end of the drill is apertured so that a stream of lubricant under relatively high pressure is directed to the point of drilling; and by means of this stream of lubricant, the chips cut by the carbide tip Se are flushed out of the hole being drilled.

On the top of each head 20, there is mounted a high speed electric motor 5S, the shaft of which is provided with a sheave 40. Motor 3S drives spindle 26 directly through a belt d2 and a sheave 4d removably mounted on the spindle. The speed of spindle 26 in relation to the speed of motor 3h can be readily varied by changing the relative sizes of sheaves iti and 44. kMotor 38 is of a conventional type which incorporates an electric brake that is automatically applied whenever the motor is deenergized. The brake is deenergized as soon as the motor is energized. i

Within head Ztl, there is keyed to spindle 26 a worm gear ad which meshes with a worm wheel 48. Worm wheel i8 is keyed to a shaft 5i? journalled in head 20 perpendicularly to spindle Z6. A second shaft 52 is also journalled in head 20 in parallel relation to shaft 50. At one side thereof, head 20 is provided with a gear box 54 closed by a removable cover plate 56 (FIG. 5). Shafts 50 and 52 project at one end into gear box 554i. Pick-olf gears 5S and 60 are keyed to the ends of shafts 50 and 52 respectively, Within gearbox 54. Gears S3 and 60 are in meshing relation and the relative speeds of the two shafts 50 and 52 can be readily changed by simply removing cover plate 5,6 and replacing the two gears 58 and di) with another set of pick-off gears of different relative sizes.

Within head 20, there is keyed to shaft 52 a second worm 62 which meshes with a worm wheel formed integrally with a nut 6d. Nut 66 is journalled for rotation in head 20 by bearings 63. Nut 5d is threadedly engaged with an axially extending lead screw 70 journalled for rotation on base lll in upright standards 72 adjacent opposite ends of base i8. At its outer or rear end, each lead screw 70 has keyed thereto a spur gear 74 which meshes with another spur gear 7d (FlG. 6) keyed to the drive shaft 78 of a rapid traverse electric motor S0. Motor S0, like motor 33, includes a brake, not illustrated, which restrains the motor shaft '7S from rotating when the motor S is deenergized. When the motor 30 is energized, the brake is released to permit rotation of the shaft 73.

lt is desirable to provide suitable limit switches S2 and Srlon base 18 which are adapted to be actuated by a detent da on headV 20. Limit switches 02 and Se are mounted for adjustment axially of base 18 on an axially extending rail 3S. The limit switch arrangement is such that when limit switch is contacted bythe advancing detent 36, motor 38 is deenergized and motor S0 is energized. On the retraction of head Ztl, when detent 8d strikes limit switch dit, motor 80 is deenergized. A suitable control panel including start and stop switches, not illustrated, is incorporated'in the machine for controling the operation thereof.

The arrangement illustrated in FIG. 1 shows a set-up for drilling a small hole horizontally through the work piece 15. The two drills 34 are axially aligned and the worl; piece le is fixture-d on the base l0 of the machine so that thc ends of the drills 34 `are aligned mially with the axis of the hole to be drilled. ln this arrangement, both heads are advanced axially toward one another. The limit switches 82, 34 for the two heads are adjusted such that one of the heads will advance its associated drill about half-way through the work and then retract and the other head will advance a slightly greater distance so as to connect the two holes drilled and thereby form one continuous hole completely through the work piece, the hole having `a perfectly straight axis. Both heads Z0 operate in exactly the same manner and a description of the operation of only one of the heads is therefore necessary.

When the start switch of the machine is actuated, motor 33 is energized. rhis causes spindle 2.6 to be rotated at a speed relative to the speed of motor 38 as determined by the size ratio between sheaves i0 and dit. The ratio between sheaves d0 and 4d will be selected in accordance with the spindle speed desired as determined by the material being drilled and the size of the hole being drilled. Rotation of spindle 26 is transmitted to shaft S0 through worm gear 46 and worm wheel d3 and in turn, shaft 52 is rotated by reason of the interengagement of the pick-olf gears 58 and 60. Thus, worm d2 is rotated at a predetermined speed in relation to the speed of motor 3S and rotation is thereby imparted to the nut ed by the worm wheel 6d. Lead screw 70 at this time is prevented from rotating by reason of its interconnection with the shaft 7S of motor $0. Thus, as the nut 66 is rotated, it is advanced along screw 70 toward the work piece. lust before the tip Edof the drill contacts the work piece, an oil pump, not illustrated, is energized to conduct oil under pressure through a conduit 9d and to the fitting 30 at the rear or outer end of spindle 26. rlfhis oil under pressure llows through the hollow spindle 26 through the collet 2S and through the drill 3d to the end thereof adjacent the cmbide cutting tip 36'. As the tip d cuts into the work being drilled, the chips formed thereby are flushed out of the hole by the oil discharged from the end of the drill. Each head 20 thereby advarices along the lead screws 70 on the guide bars 2?. until the detent S6 contacts the limit switch 82. When the limit switches S2 are actuated, motors 3S are deenergized and motors S0 are energized. rIfhus, the nut 65 is held stationary and the lead screw 70 is rotated at a speed determined by the speed of motor @il and the size ratio of bears 7e and '7o. lt will be apparent, however, that the motor {it} produces a rapid traverse of head 20 on the retraction stroke or" the heads as compared to the extremely slow rate of advance of the heads 20 during the feed cycle. ln order to protect the screws 70 from the chips flushed out of the hole being drilled, a portion of each screw l0 between the head 20 and the upright standard 72 at the inner end of base l is enclosed by a bellows member 92.

With the arrangement described herein, it will be observed that spindle 25 can be rotated at a relatively high speed, 10,000 rpm., for example, while the head 20 is advanced at an extremely slow feed rate, .0001" per revolution of spindle 26, for example. The extremely slow feed rate possible with this arrangement in relation to the speed of spindle 26 is achieved by the particular gearing employed. As described, this gearing consists of two worm drives and a single set of pick-od gears. One worm drive, that is, the worm ld and the worm wheel 4S, is directly from the spindle 2,6 and the other worm drive, that is, worm 62 and the worm wheel 64, is on the nut 66. Between these two worm drives is interposed the set of piclooif gears 58 and d0.

This simple arrangement not only enables me to reduce the speed of rotation of nut tid to an extremely low value in relation to speed of motor 3S, but also enables me to vary the speed of nut d6 by very small increments.

An example of the gear reduction possible with this arrangement will illustrate clearly the slow feed rate obtainable. Assume `a gear reduction of 25 to 1 at both worm drives, a 2 to 1 ratio at the pick-off gears 58, 60 anda lead screw 70 having a pitch of 8 threads per inch. With such an arrangement if the spindle is rotated at 10,000 rpm. shaft 50 will rotate at 400 rpm. and shaft S2 at 200 r.p.m. Nut 6d will rotate at 8 rpm. and for each revolution of spindle Zai the head 20 will advance .0001". By providing a plurality of sets of picloof gear which progressively change the gear ratio by one tooth, a progressive variation in the feed in increments of 000015" is obtainable.

Thus, with this arrangement, I am able to `accommodate the speed and feed of the spindle to any particular requirements of deep drilling, considering the type of material and the size of the hole being drilled. When one considers that the proper chip formation is under many circumstances controlled by a very critical relationship between the speed of the spindle and the feed thereof andthat a very slight change in this ratio produces a substantial change in the type fof chip formed, the desirability of the particular arrangement shown herein can be readily appreciated. The two sets of worm drives provide a maximum speed reduction with the least possible gearing. The Worm drives are capable of transmitting high torque at very high speeds. In addition, this particular arrangement reduces the noise and backlash to a minimum.

It should also be noted that the feed of the spindle is at all times synchronized with its speed. If the pick-olf gears are selected to provide a feed of .0001" per revolution of the spindle, this ratio of speed to feed will remain the same regardless of any change in speed of the spindle. This feature of my machine is also important since as pointed out previously the axial feed of the spindle in relation to its speed is very critical in many instances.

I claim:

1. In a deep drilling machine of the continuous feed type wherein the spindle is adapted to have a speed as high as about 10,000 rpm. and a feed as low as .0001 per revolution of the spindle, the combination of -a head, a hollow spindle journalled on said head and having collet means thereon for supporting a hollow drill, means for admitting liquid lubricant to the hollow spindle and through the spindle to the drill thereon, a motor for driving the spindle at a relatively high speed and means for advancing said head and spindle in a direction axially of the spindle at a relatively slow feed rate which can be varied by minute increments comprising a screw member and a nut member, one of which is axially and rotatably tixedaud the other being rotatable on the head and movable axially on the other with said head, a worm on said spindle, a pair of parallel shafts journalled on said head, one of said shafts having a worm wheel fixed thereon and meshing with said worm gear, the other shaft having a worm gear thereon, one of said screw and nut members having a worm wheel fixed thereto and meshing with said last mentioned worm gear and a pair of meshing pick-off gears lreyed to said shafts for ready removal therefrom.

2. The combination set forth in claim 1 wherein the screw member is fixed and the nut member is rotatable on the screw member `and Carr-ies the last mentioned worm wheel.

3. The combination set forth in claim 2 including means for optionally rotating said screw at a relatively fast rate as compared with the rate of rotation of the nut through the aforementioned gear train from said motor.

4. in a deep drilling machine of the continu-ous feed type wherein the spindle -is `adapted to have a speed as high as about 10,000 rpm. and a feed as low as .0001 per revolution of the spindle, the combination of a base, axially extending guide means on said base, a head on said base engaged with said guide means for movement axially therealong, said head comprising a housing, a spindle journalled -in said housing and having opposite end portions thereof projecting outwardly of the housing, said spindle being hollow and having collet means at one end thereof for supporting a hollow drill, the opposite end portion of the spindle having means thereon for conducting liquid lubricant through the spindle and collet means to the hollow drill, a motor for driving the spindle at `a relatively high speed and means for advancing the head and spindle axially along said guide means at a relatively slow rate of feed which can be varied by minute increments comprising a screw, means on said base for supporting said screw in axially fixed position and for preventing rotation of the screw, a nut journalled on said head and threaded on said screw such that when the nut is rotated, the head is shifted axially of said guide means, a worm on said spindle, a pair of parallel shafts journalled on said head, one of said shafts having a worm wheel xed thereon and meshing with said worm gear, the other shaft having a worm gear thereon, said nut having a worm Wheel thereon meshing with the last mentioned worm gear and a pair of meshing pick-off gears keyed 4to said shaft for ready removal therefrom.

5. rThe combination set forth in claim 4 wherein said housing includes a gear box, said gear box being closed.

at one side of said housing by a removable cover plate, said shafts projecting into said gear box, said pick-off gears being mounted on the portions oi' the shafts projecting into the gear box.

6. The combination set forth in claim 4 including a motor having a normally non-rotatable shaft which is driven when the motor is energized and means operably connecting said motor shaft with said screw.

7. in a deep drilling machine yof the continuous feed type wherein the spindle is adapted to have a speed as high `as about 10,000 rpm. and a feed as low as .0001" per revolution of the spindle, the combination of a base, axially extending guide means on said base, a head on said base engaged with said guide means for movement axially therealong, said head comprising a housing, a spindle journalled in said housing and having opposite end portions thereof projecting outwardly of the housing, said spindle being hollow and having collet means at one end thereof for supporting a hollow drill, the opposite end portion of the spindle having means thereon for conducting liquid lubricant through the spindle and collet means to the hollow drill, a motor for driving the spindle at a relatively high speed and means for advancing the head and spindle axially along said guide means at ya relatively slow rate of feed which `can be varied by minute increments comprising a screw, means on said base for supporting said screw in axially fixed position and for preventing rotation of the screw, a nut journalled on said ead and threaded on said screw such that when the nut is rotated, the head is shifted axially of said guide means, a worm on said spindle, a pair yof parallel shafts journalled on said head, one of said shafts having a worm wheel xed thereon and meshing with said worm gear, the other shaft having ya worm gear thereon, said nut having a worm wheel thereon meshing with the last mentioned Worm gear and a pair of meshing pick-olf gears keyed lto said shaft for ready removal therefrom, said motor including a driven shaft, a sheave removably mounted on said shaft, one end portion of said spindle projecting out of said housing having a sheave thereon, said last mentioned sheave being readily removable from the spindle and a belt extending yaround and oper-ably connecting said sheaves.

S. The combination set forth in claim 7 wherein said motor shaft -is non-rotatable when the motor is deenergized.

9. ln a deep drilling machine of the continuous feed type wherein the spindle is adapted to have a speed as high as about 10,000 r.p.m. and a feed as low as .0001 per revolution of the spindle, the combination of a head, a hollow spindle journalled on said head and having collet means thereon for supporting a hollow drill, means for admitting liquid lubricant to the hollow spindle and through the spindle to the drill thereon, a motor for driving the spindle at a relatively high speed and means for advancing said head and spindle in a direction axially 'of the spindle at a relatively slow feed rate which can be varied by minute increments comprising a screw member and a nut member, one of which is axially and rotatably iixed and the other being rotatable on the head and movable axially on the other with said head, a worm on said spindle, a pair of parallel shafts journ-alled on said head, one of said shafts having a worm wheel fixed thereon and meshing with said worm gear, the other shaft having a worm gear thereon, oneof said screw and nut members having a worm wheel iixed thereto and meshing with said last mentioned worm gear and a pair of meshing pick-off gears keyed to said shafts for ready removal therefrom, the drive between Ithe motor and the spindle comprising a sheave removably mounted on the motor shaft, -a sheave removably mounted on the spindle and ya belt extending 'around and operably connecting said sheaves.

References Cited in the file of this patent UNITED STATES PATENTS 447,713 Sponsel Mar. 3, 1891 578,431 Tucker Mar. 9, 1897 2,054,760 Oberhoifken Sept. 15, 1936 2,630,724 Saives Mar. l0, 1953 

1. IN A DEEP DRILLING MACHINE OF THE CONTINUOUS FEED TYPE WHEREIN THE SPINDLE IS ADAPTED TO HAVE A SPEED AS HIGH AS ABOUT 10,000 R.P.M. AND A FEED AS LOW AS .0001" PER REVOLUTION OF THE SPINDLE, THE COMBINATION OF A HEAD, A HOLLOW SPINDLE JOURNALLED ON SAID HEAD AND HAVING COLLET MEANS THEREON FOR SUPPORTING A HOLLOW DRILL, MEANS FOR ADMITTING LIQUID LUBRICANT TO THE HOLLOW SPINDLE AND THROUGH THE SPINDLE TO THE DRILL THEREON, A MOTOR FOR DRIVING THE SPINDLE AT A RELATIVELY HIGH SPEED AND MEANS FOR ADVANCING SAID HEAD AND SPINDLE IN A DIRECTION AXIALLY OF THE SPINDLE AT A RELATIVELY SLOW FEED RATE WHICH CAN BE VARIED BY MINUTE INCREMENTS COMPRISING A SCREW MEMBER AND A NUT MEMBER, ONE OF WHICH IS AXIALLY AND ROTATABLY FIXED AND THE OTHER BEING ROTATABLE ON THE HEAD AND MOVABLE AXIALLY ON THE OTHER WITH SAID HEAD, A WORM ON SAID SPINDLE, A PAIR OF PARALLEL SHAFTS JOURNALLED ON SAID HEAD, ONE OF SAID SHAFTS HAVING A WORM WHEEL FIXED THEREON AND MESHING WITH SAID WORM GEAR, THE OTHER SHAFT HAVING A WORM GEAR THEREON, ONE OF SAID SCREW AND NUT MEMBERS HAVING A WORM WHEEL FIXED THERETO AND MESHING WITH SAID LAST MENTIONED WORM GEAR AND A PAIR OF MESHING PICK-OFF GEARS KEYED TO SAID SHAFTS FOR READY REMOVAL THEREFROM. 